The Sound and the Jury

A birding acquaintance I run into in the field periodically called the other evening and delivered himself of a vituperative rant inspired by angst and frustration with bird calls and songs and high frequencies and a cabal of auditory birders hell bent on making aural identification more important than actually seeing a bird:

“I’m getting sick and tired of all these {expletive deleted} birders holding forth about how much more important hearing an {expletive deleted} bird is than {expletive deleted} seeing one there’s this one {expletive deleted} at Cornell claims he can tell nine different subspecies of red crossbills by their calls alone by recording them in the middle of night during migration and comparing their sonograms with some {expletive deleted} software and if I read another post about bird calls having more meaning than actual {expletive deleted} sightings I’ll scream because what the {expletive deleted} is more important that seeing the {expletive deleted bird!”

Soon as I heard my acquaintance’s tone of voice I put him on speakerphone, dashed over to the kitchen cabinet and grabbed a wine glass, only to reassess the situation and exchange it for a drink glass, feeling almost certain that any measured response to this cataract of invective would require strong drink.

I had enough time to pour myself four fingers of a peaty single malt Scotch before he caught his breath and started in again, saying,

“So what do you think about all this {expletive deleted} about calls and songs and frequencies nobody can hear being more important than solid {expletive deleted} field identification?”

I took a long, slow, wonderful sip of Scotch.

“You there?”

I acknowledged my presence and started to address some of my acquaintance’s concerns and complaints, beginning by admitting up front that I knew the guy at Cornell who could identify nine subspecies of red crossbill, adding, admonishedly, that no one could possibly identify the subspecies in the field, no matter how good a look they got of the bird, no matter how good a photo they took.

Before he had a chance to speak I launched into a pretentious disquisition on how the fifty-first supplement to the American Ornithological Union’s Check-list of North American Birds had, I suspect for the first time, identified the vast majority of new species added to the list based on sounds rather than genetic evidence, indeed, while acknowledging “very sketchy genetic data.” I explained that eight of the eleven newly recognized species received species status based on their calls or songs, which several of the AOU’s naming and classification committee members considered “compelling” evidence of “immediately diagnosable” differences among species.

Some committee members went so far as to say that the new burden of proof now falls on presenting evidence that the newly described species do not differ from a species with identical looks but demonstrably different vocal arrays, instancing the biological species concept, the mechanism that isolates a species and prevents interbreeding because of distinctive vocalizations.

“No {expletive deleted}?”

I didn’t let up but launched into a prolix description of some research about birds and urban noise that presents thirty years of data documenting an increase in the frequencies of bird songs and calls that correlates one hundred percent with increasing traffic noise in a large city, the underlying assumption being that birds hear each other more clearly if they sing and call at a higher frequency than the rumble of traffic and the bustle of crowds, the roar of the greasepaint. Moreover, I emphasized, this amazing adaptation to their environment got passed along to the birds’ offspring sort of like genetic information.

My acquaintance cleared his throated but didn’t say anything.

I went on about yet another study that demonstrated a one hundred percent correlation between the song frequencies of several common urban species and ambient traffic noise, and then noted in passing that someone else plans to publish a study demonstrating a one hundred percent correlation between the frequencies of white-crowned sparrow songs and increases in the vegetation density in their habitat.

“What about bird population estimates? Is hearing them as important as everybody seems to think?”

I told my acquaintance that the primary database of bird populations in the United States relied almost exclusively on auditory data, that the protocol for estimating the population in a given area involved driving a very specific route, stopping every quarter mile or so and, simply, listening. You have to do it at a very specific time of year, and follow the protocol assiduously, if you want to collect data ornithologists can extrapolate into meaningful population estimates.

My acquaintance, sounding very sweet and ingenuous, thanked me, then asked, chirpingly , in a higher frequency than his rant,